Distinguishing Between Chemical And Physical Changes

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Lab Title: Distinguishing Between Chemical and Physical Changes in Matter Purpose: The objective of this lab is to determine if there are chemical or physical changes that occur after mixing various forms of matter. To do this the following items are mixed together and macroscopic changes are observed and recorded: Starch + I2, Food coloring + NaOCl, Food coloring + CH3COOH, Red cabbage + NH3, Red cabbage + CH3COOH, NaHCO3 + NH3, NaHCO3 + CH3COOH, Na2CO3 + CH3COOH, MgSO4 + CH3COOH, MgSO4 + NH3 and MgSO4 + Na2CO3. Materials: test tubes, cups, coffee filters, pipettes, red cabbage, distilled water, blue food coloring, Epsom salts (MgSO4), washing soda (Na2CO3), baking soda (NaHCO3), potato starch, vinegar (CH3COOH), bleach (NaOCl), clear ammonia (NH3), and iodine (I2). Procedure: Before performing the experiments, de-clutter and clean the workstation, read the instructions and make sure to know how to operate all equipment. Next, predict the outcomes of each experiment. Then, put on the safety goggles and create the solutions. The red cabbage indicator solution takes the longest to make. Therefore, it is wise to make this first. To do this, cut up half a head of cabbage, immerse it in a pan with distilled water, cover the pan and heat the pan until the water boils. Boil for five minutes, then turn off the heat and let the pan and its contents cool to room temperature. Next strain the contents of the pan through the coffee filter. The goal is to remove the cabbage and be left with only the purple liquid solution. Discard the cabbage and keep the purple solution. Next, prepare the rest of the solutions and label the cups in which they are being deposited: • Compose the MgSO4 solution by combining approximately ¼ teaspoon (tsp.)... ... middle of paper ... ...leting this lab in the future it would help to record the temperatures of the combining solutions to determine if there was a change in temperature and therefore a chemical reaction. Also, it would be wise to close the windows and perform the experiment in a more enclosed space. No changes in smell were noted during this experiment. It is possible that this occurred but was not noted because the experiment took place in a room with a breeze and the smells could have dissipated before they could be noted. Most importantly, it would be helpful if studies were done on the final solution to determine if it is indeed a different chemical composition than the starting matter. Reference: Brown, T. L., LeMay, H. E., Jr., Bursten, B. E., Murphy, C. J., Woodward, P. M., & Stoltzfus, M. W. (2015). Chemistry: The Central Science (Vol. 13). Pearson Education, Inc.

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